Nuclear Radiation

Question 1

Describe a demonstration to show that a particular source emits both beta particles and gamma radiation.

Answer 1

• Use a Geiger muller tube to measure background radiation with no source.
• Place source 10 cm from the tube and record count rate
• Repeat with 1-3 mm of aluminium
• The count rate shouldn’t change with or without the aluminium

Question 2

Define nuclear activity.

Answer 2

The number of nuclei that decay per second (Becquerels)

Question 3

Describe alpha radiation

Answer 3

The radiation of a particle containing two protons and two neutrons. It is strongly ionising, slow moving and positively charged so therefore deflected by a magnetic field.

Question 4

Define atomic mass unit

Answer 4

1/12th the mass of a carbon-12 nuclei

Question 5

Define beta minus radiation

Answer 5

Radiation consisting of a high energy electron that is mildly ionising, fast moving and negatively charged so therefore deflected by a magnetic field.

Question 6

Describe beta plus radiation

Answer 6

Radiation that consists of a high energy positron that is mildly ionising, fast moving and positively charged, so therefore deflected by a magnetic field in the opposite direction to beta minus.

Question 7

Define binding energy

Answer 7

The energy required to split a nucleus into its individual nucleons.

Question 8

What is a control rod?

Answer 8

A rod that is inserted into a reaction vessel that stops neutrons preventing them from continuing on to cause more fission reactions. These are mode from substances that absorb neutrons without fissioning themselves (boron).

Question 9

What is the coolant used for?

Answer 9

A fluid passed round the vessel to remove any thermal energy produced. Used to generate steam and create electricity

Question 10

What is the critical mass for a nuclear reaction?

Answer 10

The minimum amount of fissile substance needed to maintain a chain reaction and a steady flow of fission.

Question 11

What is the fuel rod.

Answer 11

Contains fissile material, each rod has many pellets of nuclear fuel which which mean the reactions are comtrolled

Question 12

Describe gamma radiation.

Answer 12

High energy photons, it is weakly ionising, travels at the speed of light and has no charge so is not deflected by electromagnetic fields.

Question 13

What is half life?

Answer 13

The time taken for half of the radioactive nuclei to decay

Question 14

What is the moderator (fission)

Answer 14

A substance that reduces the speed of neutrons released from fission.

Question 15

Define nuclear fission.

Answer 15

He splitting of large nuclei to produce smaller nuclei, fast moving neutrons and energy

Question 16

Define nuclear fusion.

Answer 16

The fusing of two smaller nuclei to form a single nuclei producing a large quantity of energ. Very high temperatures and pressures are needed as well as high magnetic fields to contain the fusing plasma.

Question 17

What is the mass defect?

Answer 17

The difference between the mass of the nuclei and its individual components. If this mass defection is large and positive then when a nuclei undergoes fission this mass defect is released as energy. If this mass defect is negative then when two nuclei are fused, energy is released.